• Journal of Institute of Control, Robotics and Systems
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• 제22권10호
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• pp.817-825
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• 2016

In this paper, we introduce a flexible gripper that we have engineered to precisely pinch in parallel and compliantly grasp objects. As found in most conventional industrial grippers, the parallel pinching property is essential for precise manipulation. On the other hand, the grippers with a flexible structure are more adept at grasping objects with arbitrary shapes and softness. To achieve these disparate properties, we introduce a flexible gripper mechanism composed of multiple flexible beam structures. Utilizing these beam structures, the proposed gripper is able to grasp arbitrarily shaped objects. Additionally, a unique combination of flexible beams enables the gripper to pinch objects using the parallel fingertips for enhanced precision. A detailed description of the proposed mechanism is provided, and an analysis of the strength and stiffness of the fingertip and finger body is presented. The Results section compares the theoretical and experimental analyses and verifies the properties and performance of the proposed gripper.

• The Korean Journal of Emergency Medical Services
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• 제21권1호
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• pp.99-109
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• 2017

Purpose: There is no recommended bag-squeezing technique for emergency medical providers to maintain correct tidal volume during mechanical ventilation. This study compared the tidal volume of two different bag-squeezing techniques during mechanical ventilation. Methods: The subjects were 38 paramedic students who were trained in airway management techniques. Two different bag-squeezing techniques were used with a bag valve mask on an intubated manikin: a conventional technique and a finger-marked, in which the bag is squeezed until the thumb and the middle finger come into contact. Hand size and grip strength were measured and analyzed statistically. Results: The mean tidal volumes for the finger-marked were significantly higher than those for the conventional technique ($542.6{\pm}35.92mL$ versus $338.0{\pm}111.15 mL$, p<.001). There was a correlation between the two techniques (Pearson $x^2=1.160$, p<.001). The subject's characteristics, including sex, hand size, and grip strength, showed no correlation with tidal volume. Conclusion: A finger-marked bag-squeezing technique provides adequate and correct tidal volumes during mechanical ventilation.

• Physical Therapy Rehabilitation Science
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• 제12권1호
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• pp.33-42
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• 2023

Objective: This study aims to analyze the effect of regular exercise through the combined walking-oriented aerobic and resistance exercises using EX1 in young adults. Design: Experimental one group pre and post test Methods: Participants comprised17 healthy young adults. All subjects performed a combined exercise program for 10 times using EX1. We measured quadriceps muscle thickness using ultrasound. Additionally, the hand grip strength test, and sit and reach test were performed before and after the exercise. Through paired t-test, we investigated whether there was a statistically significant difference in the measurement results after exercise program. Results: The rectus femoris muscle contraction ratio showed significant difference after exercise(P< 0.01). In the sit and reach test, flexibility showed significant difference after exercise(P < 0.01). The hand grip strength test also showed significant difference after exercise(P < 0.05). Conclusions: Healthy young adults can effectively perform various exercises commonly performed in daily life using EX1.

• Computers and Concrete
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• 제32권2호
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• pp.185-206
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• 2023

This article aimed to explore the optimization of mineral admixtures and retarding admixture for high-performance concrete. In essence, fresh concrete can be regarded as a mixture in which both coarse and fine aggregates are suspended in a cement-based matrix paste. Based on this view, the test procedure was divided into three progressive stages of binder paste, mortar, and concrete to explore their rheological behavior and mechanical properties respectively. At each stage, there were four experimental control factors, and each factor had three levels. In order to reduce the workload of the experiment, the Taguchi method with an L9(3⁴) orthogonal array and four controllable three-level factors was adopted. The test results show that the use of the Taguchi method effectively optimized the composition of high-performance concrete. The slump of the prepared concrete was above 18 cm, and the slump flow was above 50 cm, indicating that it had good workability. On the other hand, the 28-day compressive strength of the hardened concretes was between 31.3-59.8 MPa. Furthermore, the analysis of variance (ANOVA) results showed that the most significant factor affecting the initial setting time of the fresh concretes was the retarder dosage, and its contribution percentage was 62.66%. On the other hand, the ANOVA results show that the most significant factor affecting the 28-day compressive strength of the hardened concretes was the water to binder ratio, and its contribution percentage was 79.05%.

• Steel and Composite Structures
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• 제15권3호
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• pp.267-279
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• 2013

This article describes a simple and cost effective fabrication procedure by using hand lay-up technique that is employed for the manufacturing of thin-walled axi-symmetric composite shell structures with carbon, glass and hybrid woven fabric composite materials. The hand lay-up technique is very commonly used in aerospace and marine industries for making the complicated shell structures. A generic fabrication procedure is presented in this paper aimed at manufacture of plain Carbon Fabric Reinforced Plastic (CFRP) and Glass Fabric Reinforced Plastic (GFRP) shells using hand lay-up process. This paper delivers a technical breakthrough in fabrication of composite shell structures without any joints and wrinkling. The manufacture of stiffened CFRP shells, laminated CFRP shells and hybrid (carbon/glass/epoxy) composite shells which are valued by the aerospace industry for their high strength-to-weight ratio under axial loading have also been addressed in this paper. A fabrication process document which describes the major processing steps of the composite shell manufacturing process has been presented in this paper. A study of microstructure of the glass fabric/epoxy composite, carbon fabric/epoxy composite and hybrid carbon/glass/fabric epoxy composites using Scanning Electron Microscope (SEM) has been also carried out in this paper.

• Journal of the Korean Society for Precision Engineering
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• 제23권11호
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• pp.85-92
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• 2006

For the improvement of a conventional railway speed, tilting train(Tilting Train express) is under the development aiming for a maximum speed 180km/h. Compared to the existing conventional rolling-stock, tilting train could take an advantage of speed improvement about $20{\sim}30%$ on curve sections due to the improvement of cowing performance. However, this speed increasement creates a severe load at wheels, thus it is necessary to study the safety of wheel for tilting train preferentially. On the other hand, it is under consideration that the wheel for conventional railway rolling-stock at speeds of 150km/h will be applied to tilting train at speeds of 180km/h. In this paper, we have studied the strength of wheel structure, the geometrical contact characteristics, and the dynamic performance of wheel to evaluate the safety of wheel for tilting train.

• Proceedings of the Korean Society For Composite Materials Conference
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• 한국복합재료학회 2005년도 춘계학술발표대회 논문집
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• pp.257-260
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• 2005

Graphite reinforced conductive polymer composites were fabricated by the compression molding technique. Graphite powder was mixed with an phenol resin to impart electrical property in composites. The ratio and particle size of graphite powder were varied to investigate electrical conductivity of cured composites. In this study, graphite reinforced conductive polymer composites with high filler loadings(>66wt.%) were manufactured to accomplish high electrical conductivity. With increasing the loading ratio of graphite powder, the electrical conductivity and flexural strength increased. However. above 80wt.% filler loadings, flexural strength decreased due to lack of resin. Regardless of graphite particle size, electrical conductivity wasn’t varied. On the other hand, with decreasing particle size, flexural strength increased due to high specific surface area.

• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.637-642
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• 2002

In this study, the experiments of recycled aggregate concrete with fly ash and special blended slag powder or diatom calcined at 650$\circ$ were performed on compressive strength, shrinkage and creep. The compressive strength of concrete with recycled aggregate and pozzolanic materials were higher than that of concrete with crushed stone and OPC. On the other hand, the shrinkage and creep of concrete with recycled aggregate and pozzolanic materials was smaller than that of concrete with crushed stone and OPC. Futhermore, the shrinkage and creep of recycled aggregate concrete with fly ash and special blended slag powder was a little decreased that of recycled aggregate concrete with fly ash and diatom. Relationship between compressive strength and creep coefficient was shown to the linear relation like as $\sigma$$_{c}$= -30CF＋404.4.

• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.300-303
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• 2004

In this study, the mixing contents of ceramic powder and of shrinkage-reducing agent (SRA) influencing on the strength properties of MMA-modified polymer paste were examined. Regardless of SRA content, the flexural. the compressive and the adhesive strengths of the MMA-modified polymer paste tended to increase as the mixing content of ceramic powder increased. On the other hand, those strengths of the polymer paste tended to decrease as the mixing content of SRA increased without regard to the paste content. Furthermore. the adhesive strength of MMA-modified polymer paste in a wet condition decreased about $30-40\%$ of that in an air-dry condition without regard to the mixing content of ceramic powder and SRA.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• 제48권2호
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• pp.83-90
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• 2016

Increasing the amount of filler in paper is of high interest for paper industry while maintaining its key sheet quality properties. In this study, a MFC-GCC composite, made through a co-grinding NBSK (Northern bleached softwood kraft) pulp with a ground calcium carbonate (Intracarb 60), was used as a strength aid in paper in order to evaluate a potential cost reduction through filler increase without sacrificing paper quality. Hand-sheets were made of NBSK and/or eucalyptus pulp by using white water recirculation in a Tappi sheet former and was compared its properties without or with MFC additions at different filler levels. It was found that the MFC-GCC composite has a large surface area compared to the fiber, allowing the formation of more hydrogen bonds in the web, thus giving natural strength to the paper. Overall results are encouraging that the MFC-GCC composite allows papermaker to reduce basis weight and maintain critical sheet properties.